My 53-year-old male patient is in the waiting room. Sweating a little. Blood pressure 143/90 – moderately elevated (it’s usually 125/80). This great guy, a patient of mine, father of 3, is anxiously waiting to have his PSA blood drawn.
What is PSA?
Among physician’s it’s jokingly short for “Patient Stimulated Anxiety. “ It really stands for Prostate Specific Antigen – a misnomer. It turns out that PSA is found in many other tissues and fluids other than the prostate. In males, there are PSA molecules in semen, for example.
In women, PSA molecules are found in female ejaculate (that’s right, females ejaculate too – I know you did not know that), in breast milk and amniotic fluid.
Here’s the kicker; PSA is found in a women’s blood who have cervical, uterine and breast cancer (Pummer et al. 1992, Mohajeri et al. 2011).
Ok, sorry to digress a little. I have not answered the questions – what is PSA?
PSA is a sugar molecule combined with a protein (referred to a glycoprotein in the scientific community). Its main role is to liquefy semen. You may have noticed that semen clumps up initially after ejaculation. Within a few minutes it liquefies due to the function of the molecule PSA. This “anti-clumping” aspect is important for procreation. Sperm cells swim better when they are loose and free.
PSA and men before Prostate Cancer diagnosis
Anything under 4ml/ng does not mean you don’t have prostate cancer. In fact, 15% of men with a PSA under 4 develop prostate cancer (Thompson et al. 2004)
Generally speaking PSA is age related. For example, a 40-year-old should have a PSA well under 1.0ml/ng (exception to the rule, this individual may have an infection of his prostate causing his PSA to be above 4).
A 60 year-old with a PSA of 2 may be fine.
A steady trend upward, even if the number is under 4, after three or four PSA tests may be more connected to prostate cancer once prostatitis or other benign conditions are ruled out.
FYI – prostate enlargement or BPH may also cause the PSA to increase.
Other causes of false alarms:
1. The finger before the blood draw. That’s right, a digital prostate exam before the blood draw will cause the PSA number to be higher (Collins et al. 1997).
You’d be surprised how many physicians’ do this >:-(.
Take charge. If you’re going to get the finger, get it after the blood draw.